This invention relates to provision of means to decrease the speed of an internal combustion engine if the engine overheats. This is broadly old in U.S. Pat. No. 4,459,951 which has a circuit in which a temperature sensing switch is closed when the engine overheats. This causes an oscillator circuit to progressively decrease engine speed to a "safe level." While the patent states that "if the throttle is maintained at its full open position the duty ratio will be held constant so that the engine continues its revolutions at a low speed," the fact is that when the temperature responsive switch opens the engine speed will jump back to full speed. The present invention reduces engine speed when overheat occurs and does not restore engine speed when the heat switch opens . . . this invention requires positive operator action to enable the engine speed to be restored.
In addition to U.S. Pat. No. 4,459,951 attention is directed to the following patents:
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